Twelve years after calling it quits, legendary grunge band [artist id="1019"]Soundgarden[/artist] are set to reunite in 2010. Former singer [artist id="100108"]Chris Cornell[/artist] made the long-hoped-for announcement on New Year's Eve via Twitter.

"The 12-year break is over and school is back in session," Cornell wrote. "Sign up now. Knights of the Soundtable ride again!"

The surprise revelation linked to a Web site that features a picture of the group in action during their heyday and a place for fans to enter their e-mail address to get updates on the reunion. Entering that information unlocks an archival video for the song "Get on the Snake," from the group's second studio album, 1989's Louder Than Love.

One of the most popular rock acts to emerge from the Northwest grunge scene in the late 1980s and early 1990s — alongside Nirvana, Pearl Jam and Alice in Chains — Soundgarden formed in 1984 and scored a string of hit singles with melodic hard-rock anthems such as "Black Hole Sun" and "Spoonman," anchored by singer Cornell's banshee wail and guitarist Kim Thayil's screaming notes.

Following their acrimonious split, Thayil practically disappeared from the rock map, popping up occasionally at low-key functions, but not producing any significant musical projects. Drummer Matt Cameron released several albums with his garage-rock band Wellwater Conspiracy and joined Pearl Jam as a permanent member in 1998, recording four albums with the group. Bassist Ben Shepherd released the second album by the Soundgarden side project, Hater, in 2005.

Cornell kept the busiest, recording an artsy solo album titled Euphoria Morning in 1999 and forming Audioslave with three former members of Rage Against the Machine. After releasing three albums, he left that band in 2007, dropped the introspective solo album Carry On that year and then teamed up with hip-hop producer Timbaland for a beat-fueled third solo album, last year's Scream, which met with mixed response.

Given Cornell's success with Audioslave and the lingering bad feelings following Soundgarden's split, a reunion seemed unlikely.

"It's almost like we sealed the lid and said this is Soundgarden and this is its lifespan and put it out there and it looks really great to me," Cornell told the Seattle Post-Intelligencer in 2005. "I think getting back together would take the lid off that and then could possibly change what up to now to me seems like the perfect lifespan of the band. I can't think of any reason to mess with that."

But rumors of a possible Soundgarden reconciliation began spreading last year when all the members of the band except Cornell performed in public for the first time together since 1997 at a March stop on Rage guitarist Tom Morello's solo tour in Seattle. At the time, Thayil, Shepherd and Cameron were joined by fellow grunge vet Tad singer Tad Doyle for a short set that included "Spoonman," "Hunted Down" and "Nothing to Say." A short time later, Cornell said that if he'd been in town, he might have jumped up onstage as well.

The singer told Rolling Stone in July that the band was considering releasing a B-side album and a box set of unreleased tunes. In October, he joined Pearl Jam and Cameron onstage for a run through "Hunger Strike," the hit by the grunge-era supergroup Temple of the Dog. Thayil and Shepherd were in the crowd for that gig and reunion discussions reportedly began soon after.

Billboard reported that the group is weighing offers for several major U.S. and international festivals and is in the midst of plotting a tour around Cameron's prior commitment to a spring and summer swing with Pearl Jam.